Deflectable renal nerve ablation catheter

ABSTRACT

Medical devices including catheters for renal nerve ablation and/or modulation as well as methods for making and using such devices are disclosed. An example catheter may, have a proximal region and a distal region. The catheter may be configured to shift between a first straightened configuration and a second deflected configuration. The catheter may also include an ablation member coupled to the distal region and a handle coupled to the proximal region. The handle may include an actuation member for shifting the catheter between the first configuration and the second configuration. A lock may be coupled to the handle that maintains the catheter in either the first configuration or the second configuration.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to U.S.Provisional Application Ser. No. 61/562,200, filed Nov. 21, 2011, theentirety of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure pertains generally to medical devices. Moreparticularly, the disclosure pertains to deflectable renal nervemodulation and/or ablation catheters.

BACKGROUND

A wide variety of intracorporeal medical devices have been developed formedical use, for example, intravascular use. Some of these devicesinclude guidewires, catheters, and the like. These devices aremanufactured by any one of a variety of different manufacturing methodsand may be used according to any one of a variety of methods. Of theknown medical devices and methods, each has certain advantages anddisadvantages. There is an ongoing need to provide alternative medicaldevices as well as alternative methods for manufacturing and usingmedical devices.

SUMMARY

Medical devices as well as methods for making and using medical devicesare disclosed. An example medical device may include a catheter having aproximal region and a distal region. The catheter may be configured toshift between a first straightened configuration and a second deflectedconfiguration. An ablation member or ablation members may be coupled tothe distal region. A handle may be coupled to the proximal region. Thehandle may include an actuation member for shifting the catheter betweenthe first configuration and the second configuration. A lock may becoupled to the handle for maintaining the catheter in either the firstconfiguration, the second configuration, or at any point between the twoconfigurations.

Another example medical device may take the form of a device forablating nerves disposed adjacent to a renal blood vessel. The medicaldevice may include a renal nerve ablation catheter having a proximalregion and a distal region. A pull wire may be coupled to the catheter.The pull wire may be configured to shift the catheter between a firststraightened configuration and a second deflected configuration. Anablation member or ablation members may be coupled to the distal region.A handle may be coupled to the proximal region. The handle may include acarriage coupled to the pull wire and a slider button coupled to thecarriage. A lock may be positioned within the handle and disposedadjacent to the catheter. The lock may be configured to maintain theconfiguration of the catheter.

An example method for ablating renal nerves may include providing arenal nerve ablation catheter. The catheter may include a catheter bodyhaving a proximal region and a distal region, a pull wire coupled to thecatheter body, an ablation member coupled to the distal region, a handlecoupled to the proximal region, and a lock positioned within the handle.The pull wire may be configured to shift the catheter body between afirst straightened configuration and a second deflected configuration.The handle may include a carriage coupled to the pull wire and a sliderbutton coupled to the carriage. The lock may be configured to maintainthe configuration of the catheter body. The method may also includeadvancing the ablation catheter through a body lumen to a positionadjacent to renal nerves and actuating the slider button. Actuating theslider button may pull the pull wire and shift the catheter body fromthe first configuration to the second configuration. The method may alsoinclude releasing the slider button. Releasing the slider button maycause the lock to maintain the catheter body in the secondconfiguration.

The above summary of some embodiments is not intended to describe eachdisclosed embodiment or every implementation of the present invention.The Figures, and Detailed Description, which follow, more particularlyexemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of thepresent disclosure and together with the description, serve to explainthe principles of the disclosure.

FIG. 1 is a schematic view illustrating an example renal nervemodulation system.

FIG. 2 is a schematic view illustrating the location of the renal nervesrelative to the renal artery.

FIG. 3 is a side view of an example catheter in a straightenedconfiguration.

FIG. 4 is an alternative side view of an example catheter in a deflectedconfiguration.

FIG. 5 is a cross-sectional side view of a portion an example medicaldevice.

FIGS. 5A-5B are graphs that schematically illustrate how a lockingmechanism with lower friction may provide enhanced tactile feel.

FIG. 6 is a cross-sectional side view of a portion of the examplemedical device shown in FIG. 5 in a second or “unlocked” configuration.

FIG. 7 is cross-sectional side view of a portion of another examplemedical device.

FIG. 8 is cross-sectional side view of the example medical device shownin FIG. 7 in a second or “unlocked” configuration.

FIG. 9 is cross-sectional side view of another example medical device.

FIG. 10 is a cross-sectional side view of the example medical deviceshown in FIG. 9 in a second or “unlocked” configuration.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about,” whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the terms “about” may include numbers thatare rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and5).

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The drawings, which are not necessarily to scale, depictillustrative embodiments and are not intended to limit the scope of theinvention.

It is noted that references in the specification to “an embodiment”,“some embodiments”, “other embodiments”, etc., indicate that theembodiment described may include a particular feature, structure, orcharacteristic, but every embodiment may not necessarily include theparticular feature, structure, or characteristic. Moreover, such phrasesare not necessarily referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with one embodiment, it should be understood that suchfeature, structure, or characteristic may also be used connection withother embodiments whether or not explicitly described unless clearlystated to the contrary.

Certain treatments may require the temporary or permanent interruptionor modification of select nerve function. One example treatment is renalnerve ablation which is sometimes used to treat conditions related tohypertension, congestive heart failure, or other conditions. The kidneysproduce a sympathetic response to congestive heart failure, which, amongother effects, increases the undesired retention of water and/or sodium.Ablating some of the nerves running to the kidneys may reduce oreliminate this sympathetic function, which may provide a correspondingreduction in the associated undesired symptoms.

Many nerves (and nervous tissue such as brain tissue), including renalnerves, run along the walls of or in close proximity to blood vesselsand, thus, can be accessed intravascularly through the walls of theblood vessels. In some instances, it may be desirable to ablateperivascular nerves using a radio frequency (RF) electrode. In otherinstances, the perivascular nerves may be ablated by other meansincluding application of thermal, ultrasonic, laser, microwave, andother related energy sources to the vessel wall.

Renal nerve ablation may require precise control of the catheter duringtreatment. Because the nerves may be hard to visualize, treatmentmethods employing such energy sources have tended to apply the energy asa generally circumferential ring to ensure that the nerves aremodulated. However, such a treatment may result in thermal injury to thevessel wall near the electrode and other undesirable side effects suchas, but not limited to, blood damage, clotting, weakened vessel wall,and/or protein fouling of the electrode. Once the desired tip deflectionis achieved, the operator must maintain that position stably duringablation. Afterward, the catheter can be straightened and repositionedfor additional ablation, if desired. Catheter control is enhanced bytactile feedback, to help the user apply appropriate force between thecatheter and the surrounding tissue. Tactile feedback takes advantage ofthe user's sense of touch by relaying forces to the user.

Some embodiments of the present disclosure include a medical device forablating a target tissue within a patient's body. The medical device maytake the form of a catheter having a deflectable distal end. Thecatheter may be configured to ablate a desired body tissue by, forexample, applying RF energy. The catheter's handle may include amechanism for remotely manipulating the distal end of the catheter.Further, the handle may include a locking mechanism that can assist inlocking the deflected catheter tip in a desired direction. For example,the handle may include a pivot plate lock mechanism, a roll pindeflection lock mechanism, or a tilt plate deflection lock mechanism. Inaddition, an actuator such as a slider may be actuated to deflect andlock the distal end of the catheter in the desired direction. These arejust examples.

Some catheters may include a convention friction lock handle that maylock a catheter in a deflected configuration by coupling the pull wireto the handle using a simple friction lock. The force the user feelswhen using this handle in free space is the combination of the internalhandle sliding friction (which may be significant to prevent positionloss at a maximum deflection) and the force required to deflect thecatheter (which is typically a linear function of pull wiredisplacement).

In addition, the locking mechanisms disclosed herein may also befabricated to be low friction locking mechanisms such that the forcesbetween the catheter tip and the vessel wall are more easily felt by theclinician than friction forces that may be present in the lockingmechanism itself. Because of this, the clinician may more easily be ableto detect whether or not the catheter tip has engaged the vessel wall.The design of the locking mechanisms that are contemplated (e.g.,including those example locking mechanisms disclosed herein) include astructural balance between providing sufficient locking force whilestill providing lower friction and increase tactile feedback. Suchdesigns may including, among other things, levers, tapered structures,inclined surfaces and/or structures, angled members, or the like thatcan provide at least some of these features.

The locking mechanisms may also lock the pull wire only when the user isno longer moving an actuator or slider. Because of this, the force theuser feels is essentially only the force required to deflect thecatheter. In the confined space of an artery, when the deflectedcatheter makes contact with the vessel wall, it may be much easier for auser to detect vessel contact with the low friction handles and lockingmechanisms disclosed herein, for example, because the friction in theconventional handles “mask” the effect of the change in the force versuspull wire displacement slope at a given handle actuation force.

The ablation catheter, in the following sections, may be employed tomodulate or ablate renal nerves. The ablation catheter may include asingle ablation member or electrode, a plurality of ablation electrodes,expanding basket catheters, etc. It will be understood that this choiceis merely exemplary and the catheter may be used in any desired bodylumen (including intravascular locations) requiring ablation withoutdeparting from the scope of the present disclosure.

While the devices and methods described herein are discussed relative torenal nerve modulation through a blood vessel wall, it is contemplatedthat the devices and methods may be used in other applications wherenerve modulation and/or ablation are desired. The term modulation refersto ablation and other techniques that may alter the function of affectednerves.

For purposes of this disclosure, “proximal” refers to the end closer tothe device operator during use, and “distal” refers to the end furtherfrom the device operator during use.

FIG. 1 is a schematic view of an illustrative renal nerve modulationsystem 100 in situ. System 100 may include one or more conductiveelement(s) 102 providing power to renal ablation system 104 disposedwithin a sheath 106, the details of which can be better seen insubsequent figures.

A proximal end of conductive element 102 may be connected to a controland power element 108, which supplies the necessary electrical energy toactivate the one or more electrodes at or near a distal end of the renalablation system 104. In some instances, return electrode patches 110 maybe supplied on the legs or at another conventional location on thepatient's body to complete the circuit. The control and power element108 may include monitoring elements to monitor parameters such as power,temperature, voltage, amperage, impedance, pulse size and/or shape andother suitable parameters as well as suitable controls for performingthe desired procedure. The power element 108 may control a radiofrequency (RF) electrode, which may be configured to operate at afrequency of approximately 460 kHz. It is contemplated that any desiredfrequency in the RF range may be used, for example, from 450-500 kHz. Itis, however, contemplated that different types of energy outside the RFspectrum may be used as desired, for example, but not limited toultrasound, microwave, acoustic, optical, and laser.

FIG. 2 illustrates a portion of the renal anatomy 200 in greater detail.More specifically, the renal anatomy includes renal nerves 202 extendinglongitudinally along the lengthwise dimension of renal artery 204 andgenerally within the adventitia of the artery. As will be seen in thefigure, the circumferential location of the nerves at any particularaxial location may not be readily predicted. Nerves 202 are difficult tovisualize in situ and so treatment methods may desirably rely uponablating multiple sites to ensure nerve modulation

A side view of a portion of renal ablation system 104 is shown in FIGS.3 and 4. System 104 may include a flexible, elongated catheter 302,which may include a catheter shaft 303 having its proximal end connectedto a handle 304 and having a distal tip 312 including an ablation member314 disposed adjacent to or otherwise coupled therewith. The particularconfiguration and size of the handle 304 can vary and may include anumber of different lengths, sizes, etc., as determined by theparticular needs of a given procedure. It should also be appreciatedthat the catheter handle 304 may also vary in shape based on the comfortof a user handling the renal ablation system 104. In at least someembodiments, the ablation member 314 may be an RF ablation electrode.This is just an example as other ablation members are contemplated.Handle 304 includes a handle housing 310 with a distal end region 306coupled to the catheter shaft 303 and a proximal end region 308. Adeflection wire (not shown in FIGS. 3-4, can be seen in FIGS. 5-10 andmay also be referred to as a pull wire) may be disposed within thehandle housing 310, may extend along at least portion of (e.g., alongthe interior, exterior, or both) catheter shaft 303 and be attached at aposition adjacent to distal tip 312 (e.g., adjacent to ablation member314). The deflection wire may also be connected to other structuresinside the handle 304, as discussed in more detail below.

Deflection of the catheter tip 312 may be controlled by an activedeflection mechanism (also referred to as an actuation mechanism). Theactive deflection mechanism may be located inside the catheter handle304; though it should be appreciated that the active deflectionmechanism may be located at any other suitable location. For actuation,the catheter handle 304 may also include an actuation member or a sliderbutton 316 and/or a rotating cap 318. The rotating cap 318 may or maynot be made so that it independently rotates relative to the handlehousing 310. The slider button 316 and the rotating cap 318 may bedesigned to allow user manipulation of catheter shaft 303, which mayanalogously shift the position of ablation member 314. For example,sliding the slider button 316 along handle housing 310 may shiftcatheter shaft 303 between a generally straightened configuration (e.g.,as shown in FIG. 3) and a generally deflected configuration (e.g., asshown in FIG. 4). Likewise, rotation of rotating cap 318 may rotatecatheter shaft 303. These and other elements may cooperate as part of anactuation mechanism that may be used to rotate and/or deflect thecatheter 302.

When the slider button 316 is not being operated, a locking mechanism,examples of which are discussed below, may help maintain the cathetertip 312 in either a straightened, deflected, or partially deflectedstate. Once the catheter tip is 312 deflected to the desired extent, theuser may release the slider button 316. That action automaticallyactivates the locking mechanism to prevent the catheter tip 312 fromreturning to the original straightened configuration. The mechanicalarrangement utilized for the structural features of renal ablationsystem 104, may help control the forces felt by the user duringdeflection so that the forces felt by the user are almost entirely thoseproduced by pressure of the catheter tip 312 against the vessel wall andthe forces required to deflect the catheter, providing superior tactilefeedback to the user. It can be appreciated that the locking mechanismcan be utilized, in at least some embodiments, to lock the catheter tip312 in a straightened configuration, a curved configuration, or anyconfiguration therebetween.

FIGS. 5-10 illustrate some of embodiments contemplated for lockingmechanisms that may be adapted to hold the catheter tip 312 in adeflected or partially deflected state. Common features of thoseembodiments can be discerned before examining particular characteristicsof each embodiment. In broad terms, the locking mechanism may include acarriage 502, shown in FIG. 5, and a carriage shaft 503. Carriage shaft503 may be coupled to the handle housing 310. In some embodiments, thecarriage shaft 503 may take the form of a metal rod. Other forms arealso contemplated. Carriage 502 is generally carried within handle 304,and is configured to slide distally and proximally within the handle 304along, for example, the carriage shaft 503. In at least someembodiments, the slider button 316 is also coupled to the carriage 502so that sliding motion of the slider button 316 along the outside of thehandle 304 may result in corresponding motion of the carriage 502.

Carriage 502 may include a cavity 504, extending lengthwisetherethrough. A pull wire 506 may be disposed within cavity 504. Theproximal end of the pull wire 506 may be connected to carriage 502 at afirst point (also referred to as an anchor point 508) as shown in FIGS.5-10. The distal end of the pull wire 506 may be extended and connectedto catheter shaft 303, for example at a position adjacent to distal tip312. This may include extending pull wire 506 through catheter shaft303, along an exterior surface of catheter shaft 303, both, etc. to aposition where pull wire 506 is coupled or otherwise attached tocatheter shaft 303 (e.g., at or near distal tip 312). Accordingly,movement of the carriage 502 (e.g., by actuating the slider button 316)results in movement of the pull wire 506 and deflection (and/orstraightening, depending on direction) of the catheter shaft 303. Thepull wire 506, optionally, may be disposed within a sleeve or housing510.

One embodiment of the locking mechanism that may be configured to holdcatheter shaft 303 in a deflected or partially deflected configurationis a pivot plate lock mechanism 500, shown in FIGS. 5 and 6. In theillustrated embodiment, the pivot plate lock mechanism 500 may includean actuation member 511 that may take the form of a switch handle ortoggle that may extend upward through the surface of handle 304 and beaccessible to a user. Actuation member 511 may be pivotably mounted oncarriage 502 for rotation proximally and distally around a pivot joint512. In some embodiments, the actuation member 511 (e.g., the portionextending through the handle 304) may be positioned alongside oradjacent to slider button 316. In other embodiments, the actuationmember 511 may be a structural feature incorporated into the sliderbutton 316.

Carriage 502 includes a channel 514 formed therein. A pivot plate 516may be disposed in channel 514 that is coupled to or otherwise isconfigured to ride along carriage shaft 503. The channel 514 having thepivot plate 516 is designed so that the carriage shaft 503 can slidethrough the pivot plate 516 without binding when pivot plate 516 standssubstantially perpendicular relative to the carriage shaft 503 (e.g.,which allows analogous movement of the catheter shaft 303) yet restrictmovement of the carriage 502 along the carriage shaft 503 when pivotplate 516 is “pivoted”.

One or more springs (or biasing springs) 518 may be connected to, forexample, the edge of pivot plate 516 and a transverse side of channel514, as shown in FIG. 5. For example, the spring 518 may connect to theupper edge of the pivot plate 516 or some other location. The biasingspring 518 may take the form of a coil spring or any other suitablestructure. When mechanism 500 is in a first or “locked” configuration(e.g., as shown in FIG. 5), biasing spring 518 may be configured toexert a force on pivot plate 516 so as to “pivot” the pivot plate 516,which may orient pivot plate 516 at an angle relative to the carriageshaft 503 and wedge it against the carriage shaft 503. The tilted orpivoted position of the pivot plate 516 restricts the movement of thecarriage 502 distally (e.g., toward the right on the FIG. 5) along thecarriage shaft 503.

To deflect the catheter tip 312, the user pulls the slider button 316proximally (to the left in FIG. 5). In doing so, the carriage 502 slidesproximally along the carriage shaft 503. The orientation of the pivotplate 516 allows carriage 502 to slide along the carriage shaft 503 inthis direction (e.g., the proximal direction). As the carriage 502slides along the carriage shaft 503, the tension forces in the pull wire506 increase as illustrated with the force arrow positioned adjacent tothe pull wire 506 (pointed to the right). The tension forces arebalanced by the friction forces at the contact points between the pivotplate 516 and the carriage shaft 503 (depicted with arrows pointed tothe left). Because the friction forces balance the tension forces, thecarriage is effectively “locked” from motion to the right. However, thecarriage 502 may still be permitted to slide proximally. Accordingly,the lock mechanism 500 may be described as a “one-way” lock that allowsfor proximal movement of the carriage 502 (and corresponding deflectionof the catheter shaft 303) while substantially preventing distalmovement of the carriage (and corresponding straightening of thecatheter shaft 303) when in the “locked” configuration.

To “unlock” the lock mechanism 500, the user may tilt or pivot thetoggle 511. When doing so, a leg portion 513 of toggle 511 (e.g., abottom portion or projection of toggle 511 disposed adjacent to pivotjoint 512) may exert a force onto pivot plate 516. The force from theleg portion 513 on the pivot plate 516 may overcome the bias of spring518 and allow pivot plate 516 to “pivot” to a more upright orperpendicular position relative to the carriage shaft 503. With pivotplate 516 in an upright position, carriage 502 can slide relative to thecarriage shaft 503 in either direction. This “unlocked” configuration isillustrated in FIG. 6.

Returning the toggle 511 to a more upright configuration removes orreduces the force exerted by the leg portion 513 on the pivot plate 516and allows the spring 518 to return the pivot plate 516 to the pivotedorientation (e.g., where the pivot plate 516 can wedge against thecarriage shaft 503), again “locking” the carriage 502 (e.g., preventingthe carriage 502 from moving to the right or distally). The locking maybe considered “automatic” and occur almost instantly upon release of thetoggle 511. Thus, in use the proximal movement of carriage 502 pulls thepull wire 506 (fixed to anchor point 508) in the same direction. As thepull wire 506 moves proximally with respect to shaft 303, the cathetertip 312 deflects (e.g., as shown in FIG. 4). To return the catheter tip312 to an undeflected configuration, the user can again actuate theactuation member 511 (e.g., to the “unlocked” configuration as shown inFIG. 6) and urge slider button 316 distally, which moves the pull wire506 distally with respect to shaft.

The locking mechanism 500 may impose very low friction on the system,allowing the user to feel the forces between the catheter tip 312 andthe vessel wall, providing excellent tactile feedback. For example, theforce required to deflect the catheter tip 312 (which itself mayincrease in, for example, a linear manner as the catheter tip 312 isfurther deflected) may be considerably lower than the force required todeflect a catheter tip when using a friction lock handle (which also mayincrease in, for example, a linear manner as the catheter tip is furtherdeflected). This is shown schematically in FIG. 5A. Upon contacting thevessel wall, an abrupt change in force (e.g., tending to resist furtherdeflection) may occur. Because the deflection forces may be much lowerwhen using the locking mechanisms disclosed herein, the user may be ableto readily detect this abrupt change in force whereas in conventionsystems the force may be “masked” by the higher deflection forces andmay not be as readily detected by the user. In other words, becausedeflecting the catheter tip 312 may require less force than conventionfriction based mechanisms, the relative percent change in the force thatoccurs when the catheter tip 312 contacts the vessel wall may be moreeasily perceived by the user.

The relative levels of force may be varied. For example, the forcerequired to deflect a catheter shaft (and overcome the friction of thelock) in a conventional system with a friction lock may be on the orderof about 1-5 pounds, or about 2-3 pounds, or about 2.2 pounds. Incontrast, the forces required to deflect the catheter tip may be lessthan about 1 pound, or about 0.1 to 0.5 pounds, or about 0.2 pounds.These are just examples. In at least some embodiments, the lockingmechanism 500 may reduce the amount of force needed to deflect thecatheter tip 312 by about 40-95%, or about 50-95%, or about 60-95%, orabout 70-95%, or about 80-95%, or about 85-90%. These are just examples.

In addition, FIG. 5B shows the instantaneous slope of the handleactuation force versus pull wire displacement (relative to the appliedforce at that point) for handles with either convention friction-basedlocking mechanism versus handles with low friction locking mechanismlike those disclosed herein. Again, the overall or relative change inforce is greater and more easily detectable by the user when using alower friction locking mechanism such as any of those disclosed herein.

When the desired amount of deflection is achieved, the user can releasethe actuation mechanism 511, returning pivot plate 516 to its wedgedposition. In this configuration, the actuation mechanism 511 resistsforces applied by the blood vessel walls or by the catheter elasticrecovery forces, retaining catheter tip 312 in its deflected state.Thus, the movement of the catheter tip 312 is effectively locked in thedeflected state. Repeated iterations of this movement pattern increasesthe deflection of the catheter tip 312 by moving the pull wire 506proximally with respect to the catheter shaft 303. This mechanism may besimilar to the ratcheting action in a caulking gun or similar structure.

It should be noted that while the locking mechanism 500 is generallyshown as being configured to lock or otherwise prevent the catheter tip312 from straightening when in a curved configuration, the lockingmechanism 500 can also be configured to essentially lock the cathetertip 312 in either direction.

An alternative embodiment of the active deflection mechanism is a rollpin automatic deflection lock mechanism 700, shown in FIGS. 7 and 8.This mechanism may include a lever 702 pivotably mounted inside thecarriage 502 and extending into a sliding button 704 as shown in FIGS.7-8. A roll pin 706 may be movably located in a downwardly inclined ramp708 formed in the carriage 502. A stop member 709 may also be disposedalong ramp 708 and a spring 710 may be coupled to the stop member 709.When the deflection lock mechanism 700 is in the “locked” configurationas shown in FIG. 7, the position of the lever 702 may be adjacent to theroll pin 706, and spring 710 may urge the stop member 709 so that theroll pin 706 wedges against the carriage shaft 503.

Much like the lock mechanism 500, lock mechanism 700 may also bedescribed as being a “one-way” lock that allows the carriage 502 toslide proximally along the carriage shaft 503 while substantiallypreventing the carriage 502 from sliding distally when “locked”. Forexample, the tension forces in the pull wire 506 are balanced by thefriction forces between the roll pin 706 and the carriage shaft 503.

To shift the lock mechanism 700 to the “unlocked” configuration, theuser may distally slide button 704 as shown in FIG. 8. This rotates thelever 702 into a slightly more angled orientation so that the lever 702exerts a distal force on the roll pin 706, shifting the roll pin 706 tothe right. This may also shift the stop 709 and compress the spring 710.When the roll pin 706 is shifted, the carriage 502 may move freely inthe distal direction with respect to the carriage shaft 503. Removingthe distal force from the slider button 704 allows the lever 702 to“automatically” shift back to its more upright orientation (e.g., asshown in FIG. 7) and wedge the roll pin 706 back into the carriage shaft503.

The leverage provided by lever 702 may advantageously help to reduce theactuation force and to make operation smooth and reliable. Whendesigning the actuation mechanism 700, the lever arm LA₁ defined betweena contact point between a top portion of the lever 702 and the bottomcontact point or fulcrum may be designed to be larger than the lever armLA₂ defined between the roll pin 706 (e.g., at the point of contact withbetween the lever 702 and the roll pin 706) and the fulcrum. Forexample, the length of LA₁ may be about 2-10 times larger than LA₂, orthe length of LA₁ may be about 3-9 times larger than LA₂, or the lengthof LA₁ may be about 4-6 times larger than LA₂, or the length of LA₁ maybe about 4-5 times larger than LA₂. In one example embodiment, thelength of LA₁ may be about 0.433 inches and the length of LA₂ may beabout 0.110 inches. These are just examples and other lengths and/orratios of relative lengths are contemplated for LA₁ and LA₂.

In addition to variations in the lengths of the lever arms LA₁/LA₂,other variations are also contemplated including variations in thespring stiffness of spring 710, the incline angle or configuration oframp 708, as well as other variations. Such variations may furtherreduce friction in the lock mechanism 700 and, for example, may furtherenhance the tactile feel.

In a further alternative embodiment, the active deflection mechanism isa tilt plate deflection lock mechanism 900 shown in FIG. 9 and FIG. 10.This mechanism 900 locks the carriage 502 in position when at rest,releasing that lock when the user depresses a slider. Here, the sliderbutton 316 is a cap 902 that overlies carriage 502 and is pivotablyattached to the carriage at a pivot point 904. Cap 902 can includeprotrusions designed for user handling and comfort as desired. A notch905 may be formed in the lower surface of cap 902, the notch 905 beingformed in the surface of cap 902 with an inclined slope extending towardthe distal end of cap 902. Locking action is provided in this embodimentby a tilt plate 906, a generally rectangular element carried in achannel 908 in a distal portion of carriage 502. The lower edge of tiltplate 906 may be rotatably carried in a slot 910 or other convenientmounting location at the bottom of channel 908. An aperture or otherconvenient structure in tilt plate 906 allows it to fit over thecarriage shaft 503, and it is secured in place by attachment to acompression spring 912 mounted at the upper end of channel 908, forexample above the location where the carriage shaft 503 passes throughthe carriage body. Spring 912 is sized so that in the spring'suncompressed state, tilt plate 906 stands tilted proximally, with itsupper end extending into the initial portion of notch 905. In thatposition, the tilt plate 906 engages the carriage shaft 503 so that thecarriage 502 is locked in position.

To increase or decrease the deflection of the catheter tip 312, the userfirst unlocks the carriage by depressing the cap 902, as shown in FIG.10. That action presses the inclined surface of notch 905 against theupper edge of tilt plate 906, compressing spring 912 and rotating tiltplate 906 into a generally upright position. There, tilt plate 906disengages from the carriage shaft 503, allowing carriage 502 to moveeither distally or proximally. To increase the deflection of cathetertip 312, the user moves carriage 502 proximally, which moves the pullwire 506 with respect to shaft 303 and deflects catheter tip 312 asshown in FIG. 4. Conversely, moving carriage 502 distally decreases thedeflection of catheter tip 312, as discussed above.

Although the embodiments described above have been set out in connectionwith a renal nerve ablation catheter, those of skill in the art willunderstand that the principles set out there can be applied to anycatheter or endoscopic device where it is deemed advantageous to deflectthe tip of the device. Conversely, constructional details, includingmanufacturing techniques and materials, are well within theunderstanding of those of skill in the art and have not been set out inany detail here. These and other modifications and variations are wellwithin the scope of the present disclosure and can be envisioned andimplemented by those of skill in the art.

Other embodiments of the present disclosure will be apparent to thoseskilled in the art from consideration of the specification and practiceof the embodiments disclosed herein. It is intended that thespecification and examples be considered as exemplary only, anddeparture in form and detail may be made without departing from thescope and spirit of the present disclosure as described in the followingclaims.

What is claimed is:
 1. A medical device, comprising: a catheter having aproximal region and a distal region; wherein the catheter is configuredto shift between a first straightened configuration and a seconddeflected configuration; an ablation member coupled to the distalregion; a handle coupled to the proximal region; wherein the handleincludes an actuation member for shifting the catheter between the firstconfiguration and the second configuration, and wherein a pull wire iscoupled to the actuation member; and a lock coupled to the handle formaintaining the catheter in either the first configuration or the secondconfiguration, wherein the lock includes a carriage attached to the pullwire, a pivot plate disposed within a channel formed in the carriage anddisposed about a carriage shaft, and a biasing spring coupled to thepivot plate.
 2. The medical device of claim 1, wherein the actuationmember includes a slider that is configured to slide along an exteriorsurface of the handle.
 3. The medical device of claim 1, wherein thelock maintains the catheter in the first configuration.
 4. The medicaldevice of claim 1, wherein the lock maintains the catheter in the secondconfiguration.
 5. The medical device of claim 1, wherein prior toactuating the actuation member the pivot plate is engaged with thecarriage shaft and distal movement of the carriage relative to thecarriage shaft is prevented, and wherein pivoting the pivot plate allowsthe carriage to slide distally along the carriage shaft.
 6. A medicaldevice, comprising: a catheter having a proximal region and a distalregion; wherein the catheter is configured to shift between a firststraightened configuration and a second deflected configuration; anablation member coupled to the distal region; a handle coupled to theproximal region; wherein the handle includes an actuation member forshifting the catheter between the first configuration and the secondconfiguration, wherein a pull wire is coupled to the actuation member;and a lock coupled to the handle for maintaining the catheter in eitherthe first configuration or the second configuration, wherein the lockincludes a carriage attached to the pull wire, a roll pin disposedwithin a channel formed in the carriage and positioned adjacent to acarriage shaft, and a biasing spring coupled to the roll pin.
 7. Themedical device of claim 6, wherein prior to actuating the actuationmember the roll pin is engaged with the carriage shaft and distalmovement of the carriage relative to the carriage shaft is prevented,and wherein actuating the actuation member causes the roll pin to rollout of engagement with the carriage shaft so that the carriage can movedistally relative to the carriage shaft.
 8. A medical device,comprising: a catheter having a proximal region and a distal region;wherein the catheter is configured to shift between a first straightenedconfiguration and a second deflected configuration; an ablation membercoupled to the distal region; a handle coupled to the proximal region;wherein the handle includes an actuation member for shifting thecatheter between the first configuration and the second configuration,wherein a pull wire is coupled to the actuation member; and a lockcoupled to the handle for maintaining the catheter in either the firstconfiguration or the second configuration, wherein the lock includes acarriage attached to the pull wire, a tilt plate disposed within achannel formed in the carriage and positioned about a carriage shaft,and a biasing spring coupled to the tilt plate.
 9. The medical device ofclaim 8, wherein prior to actuating the actuation member the tilt plateis engaged with the carriage shaft so that the carriage is lockedrelative to the carriage shaft, and wherein actuating the actuationmember tilts the tilt plate so that the carriage can move relative tothe carriage shaft.
 10. The medical device of claim 9, wherein theactuation member includes a depressible button, and wherein actuatingthe actuating member includes depressing the depressible button.